Blues can be played on any amp... But to play blues you really need to get a good feeling out of what you're playing (and hearing). There's a real visceral connection there, so the obvious answer is to go try a few things out. But in order for us to help you as best we can, let us know what sort of blues you like, and what sort of guitar you'll mostly play through it.
Here's my take on each of my amps for blues playing:
Fender Blues Jr - The best all-rounder and best for portability. Gets quite dirty and has great reverb. Bulletproof.
Vox AC30 - Thick, warm dirty tones or sweeter and brighter cleans, and gets nice and lush with its reverb and tremelo.
JCM800 - Kinda similar to the AC30, but more abrasive in its dirty tones. Gets into rock territory quickly. Great with a strat or les paul. Think Gary Moore.
Fender Pro Reverb - Roy Buchanan all day long. Raunchy cleans, with a sharp attack and a 'thud' in the bass and percussive notes. Strat and tele are great here.
Overall, I love an amp (and guitar) that I can have an argument of sorts with when I'm playing. If I play it harder it dishes it straight back at me.